1. Field of the Invention
The present invention relates to a projection image display apparatus that displays a projection image on a screen and a projection optical system for use in the projection image display apparatus.
2. Description of the Related Art
In recent years, projector apparatuses have been widely used as projection image display apparatuses that display a projection image on a screen. Use of projector apparatuses facilitates upsizing of a display screen while maintaining a high resolution compared to flat panel display apparatuses such as LCDs (Liquid Crystal Displays) and PDPs (Plasma Display Panels).
Some projector apparatuses are configured to output a plurality of images for display.
In one such example, one projector apparatus projects a right-eye image and a left-eye image on each of two screens in a time-sharing manner, providing parallax between the images on the screens (see Japanese Patent No. 4052315, for example). When the thus configured projector apparatus is used, the right-eye image and the left-eye image are alternately incident on the eyes of a viewer, allowing the viewer to recognize a stereoscopic image.
In another example, the display area of a display device such as a liquid crystal display element is divided into two, and a right-eye image and a left-eye image are displayed in each of the display areas at the same time to form a stereoscopic image (see Japanese Unexamined Patent Application Publication No. 2007-271828, for example). In the projector apparatus, a relay optical system for sectioning an image is provided between a projection optical system and a display device, and once an image is formed by the relay optical system, two sections of the image are split from each other by reflective surfaces.
In still another example, an optical path switching section that switches optical paths in a time-sharing manner is provided between a projection optical system and a screen, and a plurality of images are formed side by side on the left and the right of a screen using projection light that has passed through each of the paths (see Japanese Unexamined Patent Application Publication No. 2004-279847, for example). When the thus configured projector apparatus is used, the single projector apparatus outputs for display a wide-screen image in which a plurality of images are formed side by side on the left and the right.